Ketones of the thiamine series and their production

ABSTRACT

5-MONO-SUBSTITUTED KETONES OF THE THIAMINE SERIES HAVING THE FORMULA: WHEREIN R is hydrogen or an alkyl radical and R1 is an aryl or heterocyclic radical are produced by reacting thiamine or a mineral acid salt thereof with a compound of the formula: WHEREIN R and R1 are as defined above and X and Y are independently selected from the group consisting of lower alkyl radicals.

United States Patent Klosa 1 June 27, 1972 [54] KETONES OF THE THIAMINE SERIES AND THEIR PRODUCTION [72] lnventor: Josef Klosa, Berlin, Germany v [73] Assignee: Fischer & Fischer Gmbl-l, Baden, Germany [22] Filed: May 1, 1969 21 Appl. No.: 821,077

[30] Foreign Application Priority Data Primary ExaminerAleX Mazel Assistant Examiner-R. J. Gallagher Attorney-Waters, Roditi, Schwartz & Nissen [57] ABSTRACT 5-mono-substituted ketones of the thiamine series having the CHz-CH2OII wherein R is hydrogen or an alkyl radical and R is an aryl or heterocyclic radical are produced by reacting thiamine or a mineral acid salt thereof with a compound of the formula:

wherein R and R are as defined above and X and Y are independently selected from the group consisting of lower alkyl radicals.

15 Claims, No Drawings KETONES OF THE TIIIAMINE SERIES AND THEIR PRODUCTION DETAILED DESCRIPTION The present invention relates to S-mono-substituted ketones of the thiamine (i.e. vitamin 13,) series having the formula:

wherein R is hydrogen or an alkyl radical, preferably a lower alkyl radical, and R is a substituted or unsubstituted aryl or heterocyclic radical; and it further relates to the production thereof. When used in the present specification and claims, the term "lower alkyl" refers to alkyl radicals having one to six carbon atoms, especially one to four carbon atoms. The preferred alkyl radicals are methyl and ethyl.

It has been found that compounds of formula (I), which have not heretofore been described, have pronounced pharmacological and biological properties, and exhibit good vitamin B, resorption in the intestine, a long lasting B action, and also, depending on the nature of the substituents R and R,, a settling and soothing action as well as a restorative action, and finally are effective in protecting the liver and gall bladder.

This new class of compounds of the thiamine series of the formula (I) is obtained by a novel, and surprisingly simple process which has not been previously described.

There is known a process for producing thiamine derivatives with better resorption than is the case with vitamin B,

(see H. Kobayashi, K. Yasuda and Y. Kowa, The Journal of Vitaminology 8, 252 (1962) In all these cases, the relevant compounds are obtained by a process in which the thiazole ring of the thiamine molecule is cleaved by treating the thiamine with alkali alcoholates, so that a hydrogen atom of the sulphydryl group is replaced by the alkali. The alkali salt of the thiamine is thereafter reacted with a haloalkyl compound to form an S-alkyl thiamine derivative, and in this reaction, depending on the operating conditions, the hydroxyl group may also be etherified. The opera- 4 tions must be carried out under substantially anhydrous conditions and with very involved manipulations (British Pat. No. 963,626, German Pat. No. 1,253,717, German Pat. No. 1,249,283). The yields achieved thereby are only moderate.

Be contrast therewith, it has now been found that ketones of the thiamine series of formula (I) are obtained by reacting thiamine or a mineral acid salt thereof with a compound of the formula:

wherein X and Y are independently selected from the group consisting of lower alkyl radicals, such as methyl or ethyl, and R and R, are as defined above; the reaction taking place in the presence of an alkali, preferably a mild alkali, such as sodium bicarbonate or ammonia. When an alkali salt of thiamine is used as the starting material, the separate use of alkali is unnecessary. The reaction is simple: for example, for the preparation of S B benzoylethyl thiamine of the formula:

clear solution while stirring, and with slow dropwise addition, as soon as a pH value of 7 is exceeded, fine colorless needles of the S-/3-benzoylethyl-thiamine are precipitated. With rapid dropwise addition of the ammonia, an oil initially precipitates which then solidifies into needles. A simple recrystallization from methanol provides a snow white product, in a yield of 95 percent, Le. a practically quantitative yield.

In another modification of the process in accordance with the invention, a mineral acid salt of thiamine, e.g. thiamine hydrochloride, is caused to react with B- dimethylaminopropiophenone hydrochloride in percent methanol, with the addition of an equivalent amount of sodium bicarbonate, and with heating to 50 to C. for a few minutes to form S-B-benzoylethyl-thiamine, likewise with practically quantitative yields.

The new ketones of the thiamine series of the formula (I) as thus prepared are insoluble in water and soluble in alcohols. With the aid of pharmaceutically acceptable non-toxic acids, they can be transformed into their water-soluble salts.

Suitable fl-dialkylaminoketones of the formula (ll), are for example, B-dimethyl aminoor fl-diethylaminopropiophenone and the many different types of substitution products thereof, e.g. fi-dimethylamino-p-chloro-, -p-nitro-, -p-methoxy-, -pbromo or -p-methyl-propiophenone, B-dimethylamino-mnitro-, -m-methoxy-, -m-chloro-, -m-methyl-, or -m-bromopropiophenone, B-dimethyl-amino-p-hydroxy-m-methoxypropiophenone, a-methyl-B-dimethyl amino-propiophenone, a-methyl-B-dimethylamino-p-chloropropiophenone, 1-13- dimethylamino-propionylnaphthalene, Z-B-dimethylaminopropionylthiophen, and others, or, briefly stated, any B-dialkylaminopropioketones which can be prepared by a Mannich reaction from fatty aromatic or heterocyclic ketones and dialkylamines, such as dimethylor diethylamine.

This entire reaction is very surprising, since similar reaction of B-dialkylaminopropiophenones in such an easy manner with sulphydryl groups or other simple sulphydryl compounds are unknown, and it is only in certain cases that such a reaction is known to occur, but then only in acid medium and with moderate yields. Thiamine salts, however, do not react in acid medium with ,B-dialkyl-aminopropiophenones. When such a reaction is attempted, the unchanged initial reactants are once again obtained. Thus, the unobvious novelty of the present process is demonstrated.

The new compounds are odorless.

The compounds of formula (I) and their salts may be used as a therapeutic and as an intermediate in the preparation of other therapeutics. They may be administered either alone or 0 in the form of pharmacologically active compositions in admixture with a therapeutically inert carrier or diluent.

Some examples of the advantageous preparation of the class of compounds and of the process according to the invention are given below.

EXAMPLE 1 Seventeen grams of thiamine hydrochloride, 12g. of B- dimethylaminopropiophenone hydrochloride, and 5g. of sodium bicarbonate are dissolved or suspended in ml. of 50 percent aqueous methanol. The entire reaction mixture is heated on a water bath. After 15 minutes, a clear solution fonns. Heating is continued for another l5 minutes, whereupon the solution is filtered off while warm to remove clouding substances and mechanical impurities. To the crystal-clear filtrate, twice the initial volume of water is added. After standing for a brief period, fine, colorless needles are crystallized out and are filtered ofi. Recrystallization can be effected from a large quantity of methanol.

Yield 21 g. M.p.: 88-90 C, S-B-benzoylethyl-thiamine. The product is very readily soluble in mineral acid'solution, and is precipitated as needles from the latter by adding ammonia.

Hydrochloride of S-fi-benzoylethyl-thiamine.

The free base is dissolved in alcoholic hydrochloric acid, acetone is added and the mixture is concentrated by evaporation under vacuum. The crystallineresidue is triturated with 3 4 acetone, and colorless crystals which are very readily soluble A kemn? claimed claim 1, which is -3- in water are obtained: bemyleihyl-thlmflep .155e 157o 3. A ketone as claimed in claim 1, which is S-B-(p-methylbenzoylethyD-thiamine. EXAMPLE 2 5 4. A ketone as claimed in claim 1, which is 8-3- Seventeen grams of thiamine hydrochloride and 12 g. of};- g m i g fifi z 1 h s dimethylamino p-methylpropiophenone hydrochloride are "a 'htho lath Hhi e c m w dissolved in approximately 100 ml. of water. Aqueous am- 2 g l 1 h s moniasolution is introduced dropwise into this solution while thie'no leth 1 mi m c m w 1c is stirring and at ambient temperature, until the pH value is 8 or 10 y y i a generally weak odor of ammonia still exists. The time taken A ketone as claim whlgh for the addition is about 1 hour; The reaction material first of f "'"f'P l 31 hi h s m all assumes a milky cloudiness and then colorless crystals th 1 T C Is oxprecipitate. The whole is left standing for several hours and y oxy nzoy e y i after the odor of ammonia has disappeared more am-moniais 9. A salt of the ketone as claimed in claim 1 which is the added and suction filtering is carried out. In the event that the hydrochlonde' on has not become crystalline, it is mmrated with methanol. 10. ketone as claimed in claim 1 wherein the lower alkyl Yield 22 g. M.p.: ll0l 12 c., S-B-p-methylgmupsmehylmehyl' benzoylethymfiamineu 1 1. A process for the production of a ketone of the thiamine Hydrochloride: Dissolve the free base in alcoholic Senes havingthe formula:

hydrochloric acid, add acetone and leave standing. After several hours, colorless needles precipitate. M.p.: l84-l N=C NH2 C 86 C., very readily soluble in water. C HPCHVOH In similar manner, by using various B-dialkylaminopro- H C pioketones, the compoundsasindicated in the following Table 3 C fi CH N |C=C are obtained in like yields. N-CH CH; S -CHQCH Ri TABLE R S-acylalkyl-thiarnlnes O N=CNH: \H /CH:CH1OH k} H C-fi (fllCH N(l3=C\ N-CL cm SCH:('3H(3-R ydro- R1 M.p. C. chloride Comment --CH 64-66 Colorles squares. :ss siz g see anaemia -CiHi-?3Hiii 108-110 ""iiit iii- Do.

cH-CH 162-64 H 1% HC\ s 6 H 011 112-114 Hygroscoplc.

7 H C.H Bi-(p) 116-118 Colorless needles.

8 H CH 0-CH;(m) 98-100 Do.

9 H @011 103-106 Yellowish crystal meal- JF-CH:

A what is claimed is: wherein R is hydrogen or a lower alkyl group and R, is a A ketone ogthc thiamin r s a ng th u phenyl, chlorophenyl, brom'ophenyl, methylphenyl,

"o nitrophenyl, hydroxyphenyl, methoxyphenyl, hydroxymethox- N=C NHa yphenyl, naphthyl or thienyl group, said process comprising reactin thiamine or a mineral acid salt thereof, in the v 8 H CHPCHPOH presence of a mild alkali at ambient temperature in aqueous or H 6I !C]CHzN-( J=C in aqueous-methanolic solution with a compound of the for- -ca 6H3 S-CHz(lJH(|3Ri mm: W x I .-sl. .ts .7 t it N whemmkishydrogenoraloweralkylgrougandk isa fi? CH? plienyl, chlorophenyl, bromophenyl, meth l hen l, nitrophenyl, hydroxyphenyl, methoxyphenyl, hydroxy n i etho itp y o e or y g o p. nd ater-soluble, phar- 7s maceutically acceptable, non-toxic acid salts thereof.

wherein X and Y are independently siectfiibin the group consisting of lower alkyl groups, and'R and R, are as defined above.

12. A process as claimed in claim 11 wherein the lower alkyl hydrochloride is reacted. group is methyl or ethyl. 15. A process as claimed in claim 1 1 wherein the mild alkali 13. A process as claimed in claim 11 wherein the mild alkali is sodium bicarbonate and the reaction is effected at a temis ammonia. perature of 50-60 C.

14. A process as claimed in claim 11 wherein thiamine 5 

2. A ketone as claimed in claim 1, which is S- Beta -benzoylethyl-thiamine.
 3. A ketone as claimed in claim 1, which is S- Beta -(p-methylbenzoylethyl)-thiamine.
 4. A ketone as claimed in claim 1, which is S- Beta -(pchlorobenzoylethyl)-thiamine.
 5. A ketone as claimed in claim 1, which is S- Beta -naphthoylethyl-thiamine.
 6. A ketone as claimed in claim 1, which is S- Beta -thienoylethyl-thiamine.
 7. A ketone as claimed in claim 1, which is S- Beta -(m-methoxybenzoylethyl)-thiamine.
 8. A ketone as claimed in claim 1, which is S- Beta -(m-methoxy-p-hydroxybenzoylethyl)-thiamine.
 9. A salt of the ketone as claimed in claim 1 which is the hydrochloride.
 10. A ketone as claimed in claim 1 wherein the lower alkyl group is methyl or ethyl.
 11. A process for the production of a ketone of the thiamine series having the formula:
 12. A process as claimed in claim 11 wherein the lower alkyl group is methyl or ethyl.
 13. A process as claimed in claim 11 wherein the mild alkali is ammonia.
 14. A process as claimed in claim 11 wherein thiamine hydrochloride is reacted.
 15. A process as claimed in claim 11 wherein the mild alkali is sodium bicarbonate and the reaction is effected at a temperature of 50*-60* C. 